With the development of high-speed transmission networks, optical communication becomes a trend. The WDM technology combines signal carriers with different regulated wavelengths by using a combiner at a transmitting end and then transmits the combined signal carriers through an optical fiber; a wave splitter splits apart the optical carriers of different signals at a receiving side. In order to bear a service, it is necessary for a wavelength division network management system to search out available paths first according to equipment resources and optical fiber connections thereof or cross connections thereof. The equipment resources refer to various single boards for accomplishing various functions during a carrier transmission process and various wavelength division network elements on which these single boards are located. The optical connections are divided into an intra-network element connection and an inter-network element connection; the intra-network element connection is a connection between different single boards located on one network element; the inter-network element connection is a connection between different single boards located on different network elements. The cross connection particularly refers to a cross relationship configured between backboard ports respectively belonging to two cross single boards. A light passing direction is pre-designed inside each type of single board, that is, the light which enters from a certain port will get out from a/some specific ports based on a rule; the rule which is abstracted out based on the designs of the single boards is generally called an opposite-end port rule. Specific connection rules also exist between various types of single boards, that is, the types of two given single boards determine which output port is to be used by the former single board and which input port is to be used by the latter single board when an optical connection is established.
The network management system can search out multiple paths for a service according to the opposite-end port rule of the single board after establishing an optical connection based on an inter-board connection rule. Since the connection rules of all single boards are different and some rules are very complex, a false connection will be easily established if full attention is not paid, then the path searched out is wrong and a carrier cannot send the service to a destination along this wrong path.